This invention relates to centrifugal separators in general, and more particularly to an improved arrangement for recovering energy at the pure gas outlet of such separators.
Centrifugal separators for separating fine grain particles are known in the art. Typical of such are those described in German Patents 1,220,240 and 1,507,847. In general they comprise a cylindrical centrifugal chamber with a coaxial raw gas inlet at one end and a coaxial pure gas outlet at the other end as well as tangential auxiliary gas inlets in the region of the periphery of the centrifugal chamber. These are disposed at an angle with respect to the raw inlet and carry the separated particles to a particle discharge concentrically surrounding the raw-gas inlet. Because in a centrifugal separator of this nature, the particle-laden raw gas is admitted into the centrifugal chamber with a rotary motion, the purified gas leaving at the opposite end still has a certain amount of rotation. The rotary flow continues into the pure gas line and generates unnecessarily high pressure losses therein.
Thus, it can be seen that there is a need for a device in which the energy of rotation can be recovered so that the overall pressure loss of the separator is reduced thereby.
Various types of diffusers have been suggested for the recovery of this energy. Typical is one described in Technische Stroemungslehre - Technical Fluid Dynamics - by Bruno Eck, Springer-Verlag, 1966, (particularly pg. 187.) Devices of this type, however, have had very little success in practice and furthermore have very large dimensions relative to the size of the rest of the apparatus since the recovery of the energy must take place without impact losses. Another suggestion is made in German Patent 1,278,203. In the arrangement disclosed therein, the separtor is designed with a pure gas outlet stub which is a diffuser and has its center axis inclined at an obtuse angle to the axis of the inlet nozzle so that it corresponds to the flow direction of the outgoing pure gas stream in the lateral outlet opening. This proposal also produces only a small amount of energy conversion from rotary energy into pressure energy and furthermore, requires considerable structure which is difficult to implement, particularly if the available space is limited.
In view of this, it is the object of the present invention to create a device which will recover the rotation energy without being unduly cumbersome and which will operate efficiently.